1. Field of the Invention
This invention relates to flexible embarkation-debarkation marine ladders.
2. Description of the Background Art
Chain ladders have been utilized for embarkation-debarkation service in marine applications, such as in emergencies. Such ladders are constructed for use by being hung to extend downwardly along a vertical portion of a vessel's hull.
In the conventional chain ladders, single loop, lock-link coil chains are conventionally employed.
Conventionally, the spacing between the chains is in the range of 16 to 19 inches. The top step of the ladder is conventionally approximately 24 inches from the upper end of the chain to which is attached a flashing ring.
The steps of the conventional marine ladder include two rungs providing both handhold and stepping surfaces. In the coventional marine ladders, the distance between the steps is in the range of 12 to 15 inches. The rungs are conventionally formed of wood or equivalent material, and conventionally have a width of at least 11/2 inches and a thickness of between 1 and 11/2 inches. The rungs are spaced apart a distance between 1 to 11/2 inches and are supported on the chain in such a manner as to prevent rotation. The rungs are arranged to extend horizontally when the ladder is hung vertically.
The ladder is arranged to take a static load on the steps of 700 lbs. and the chains are constructed to jointly support a static load of 2,000 lbs.
A typical embarkation-debarkation ladder is illustrated in drawing 160.017 of the U.S. Coast Gaurd, entitled "Type II Embarkation-Debarkation Ladder".
A number of such ladders built in conformity with the requirements of the Department of Transportation, United States Coast Guard, are commercially available.
One example of a rope ladder for such use is illustrated in U.S. Pat. No. 4,241,809, of Robert M. Salvarezza. As shown therein, the ladder utilizes a pair of side ropes with steps formed as a molded, one-piece hard elastomer member.